This is a sincere attempt to understand how homosexuality fits into the theory of evolution. Survival of the fittest doesn't explain why there would be gays and lesbians. They are not likely to reproduce especially back when we were a younger species. Please do not say it's bad DNA because that would be very insulting to the LGBT community. That would be even more insulting than religious opinions on the subject. It also would contradict the survival of the fittest because bad DNA would not have prevailed if this was so and there would not be any of us around today. Thanks

In our species, non-heterosexuality appears to be a combination of genetic and environmental factors. I personally believe it's got more to do with DNA than the environment, but others would disagree.Anyway, in other species, the percentage of non-heterosexuals is the same as in humans, which, IMO, also points toward DNA being the cause, seeing as how animals' environments tend to be pretty much the same within the same species.

Why does non-heterosexuality persist? My guess would be that the DNA mutation necessary for such a thing to occur is common, but not too common, as evidenced by the percentage of non-heterosexuals.

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My names are many, yet I am One.-Orion, son of Fire and Light, Sol Invictus.

Q: How would cystic fibrosis fit in with evolution ?A: Quite simple. A genetic mutation causes the cells in the lung to malfunction in a person and so fills the lungs with fluid. Some people carry the defective gene but for some reason it does not cause the condition so they go on to reproduce and so continue the defective gene. Gene can be dormant in many generations.

Q: How would cystic fibrosis fit in with God ?A: God fucked up the design on that person ? Did it deliberately because of his Plan(tm)?

Q: How Does Evolution Explain Homosexuality?A: A genetic anomaly causes the person to have sexual attraction to their own same sex.

Q: How does homosexuality fit in with God?A: It doesn't. These evil people are more powerful than God it seems as they have got around his Plan(tm) for them and are sticking their fingers up at him and laughing whilst indulging in twisted sinful practises and must all be killed in the most horrible ways to please God.

You find homosexual behaviour in many species around the world. Local beauty spot near me had two homosexual male swans who coupled up for years. Perhaps coincidence but for a short while the areas car park became a notorious dogging spot for homosexual men which horrified my mother once whilst out walking the dog and stumbling upon two such characters in full trousers down action.

Interesting question, junebug. It's come up here before; a search of the "Sexuality, Reproduction" board will find you some past discussions if you're interested.

I'm just a layman, but one plausible reason for the conservation of homosexuality is that it's possible to contribute to the perpetuation of your genetic line even without reproducing yourself. I'm a hetero male, for various reasons unlikely to have kids of my own. Yet I can and do help my sister with looking after her son, my nephew. Aside from the emotional connections, I'm clearly benefiting from aiding his development.

In any earlier era of human history, such contributions were even more crucial. Homosexual men and women could still hunt, gather, craft, stand watch over their kin, just get up and tend the babies in the middle of the night while others slept. Indeed, they still do these things.

I agree with One Above that overt homosexual behavior (actually preferring the same sex) is a combination of genetics and environment, the precise details of which aren't known yet. Clearly it doesn't happen often, but that it does happen at all shows the genetic component is widespread and therefore has yet to be selected out of the human genome.

To be clear, this is uninformed speculation, but it seems to me this means homosexuality can be seen as a neutral mutation, neither offering great benefit (or we'd see even more of it), or great disadvantage (or it would've already been selected out). There are others here with a far better grasp of genetics than I; perhaps one of them could correct me.

This is a sincere attempt to understand how homosexuality fits into the theory of evolution. Survival of the fittest doesn't explain why there would be gays and lesbians. They are not likely to reproduce especially back when we were a younger species. Please do not say it's bad DNA because that would be very insulting to the LGBT community. That would be even more insulting than religious opinions on the subject. It also would contradict the survival of the fittest because bad DNA would not have prevailed if this was so and there would not be any of us around today. Thanks

"Evolution" and "survival of the fittest" are not the same thing. Evolution is the description of the cumulative changes in a population (species) over time. "Survival of the fittest" is a colloquial term for one of the methods of evolutionary change, natural selection.

"Evolution" and "natural selection" are scientific terms; "survival of the fittest" is not.

I am concerned about overpopulation, and non-heterosexual (bisexual, so there's a reason to call it that instead of homosexuality, it's a broader term) so I tend to favor that explanation - it makes sense for us, as a species, to have some individuals not reproduce, to lessen overpopulation stresses, perhaps to help raise siblings' offspring, whatever...

A kid I used to teach in Sunday school recently came out as asexual, which is another form of non-heterosexuality, just, you know, as a point of interest, would also feed into controlling population and helping raise relatives.

I'm curious to know if population stresses "trigger" some change in behavior. There are more queer people in cities, but I'm guessing that's for other reasons

From my layman understanding there are certain hormonal compound markers that can flick genes on or off during fetal development. These markers can be passed down or stacked thus increasing or decreasing sensitivity to testosterone. I forget what journal I was reading so unfortunately I don't have a source for you. But I agree with OAA that it's a combination of genetic and environmental factors, with the environment most likely playing a much, much smaller role. The fact that homosexuality also occurs in nature should be a good indication that homosexuality isn't a "learned" behavior like many conservative Christians would lead us to believe.

I wrote a massive post but hit the "Forbidden 404"I think I use the word "sex" about 100 times - maybe that's why.

Anyway I will try to resolve it tomorrow after I've had a sleep.

Meanwhile in the briefest way let me say that variation is common (and even necessary) in the genome.There is no godly law of genetics that operates to quarantine the XY sex chromosome system from quite normal mechanisms that result in variation. There certainly is a perfectly explainable reason for the degree of conservation of the XY system for breeders, but even if the XY system where totally corrupted by out of control variations there would still be breeders - as a normal variation.

I can show (in my long post) quite easily how something as normal as gene variation and normal chromosomal behaviour during the normal process of meiosis can be expected to produce variations in sexuality - quite normally

Survival of a species is based on the survival of the group, not the individual. Wright has already touched on the fact that non-breeding adults (infertile as well as non-heterosexual) will assist in child-rearing even though not procreating themselves.

It could be that case that the percentage of non-breeding adults was exactly right to ensure the survival of the tribe with a steady and sustainable growth rate. Breed too few babies, the tribe dies out. But breed too MANY babies, and more resources are needed to see them through to adulthood. A tribe where half the adult population are spending most or all their time rearing children may not have the resources left to gather, hunt, build shelter, defend from predators, etc. A tribe where not all adults are producing babies may have had that crucial balance of sexualities to enable it to prosper.

The %age of non-heterosexual adults we have may well be the exact balance that early man needed to survive.

THOUGHT: Could Neanderthal man have been outbred because he was too heterosexual? Slightly tongue in cheek, but it could be a serious question.

Why does non-heterosexuality persist? My guess would be that the DNA mutation necessary for such a thing to occur is common, but not too common, as evidenced by the percentage of non-heterosexuals.

This is an EXCELLENT point and I completely agree. And I take the concept a bit further. Most of the mutations can persist in the breeders because in certain combinations of XY variants they still produce sufficient heterosexuality. It's only in some of the many possible combinations that the Y gene variants don't modify enough of the expression of X gene variants.

When heterosexual people don't understand homosexuals it's because they overlook that heterosexuals are instinctively heterosexual - it's not a difficult choice for heterosexuals to be heterosexual - they wake up in the morning having dreamed heterosexual. Heterosexuals don't need to be educated into making a choice to be heterosexual. Therefore we can quite confidently assume that the instinctive aspects of heterosexuality have genetic underpinnings which are switchable - with gene control mechanisms and responses to hormones and pheromones. There are many genes involved i.e. multifactorial. ALL these genes are subject to variation - that is just a normal consequence of being a gene in a living reproducing system.

So we have many genes involving the physical apparatus, for penises, ovaries etc, but also many genes involving the mental aspects, orientation and magnitude of sex drive. A complex system involving many gene interactions with normal variation in every component. As such there is no godly guarantee that every combination of all the gene variants available will always produce an identical outcome. If fact there is a spectrum of outcomes - physical and mental. Whip out a bunch of penises and compare them. Ask a bunch of people how often and how they like to have sex and you'll get an astonishing range of answers.

About 2% of humans have zero sex drive - others get in jail for having too much sex drive. Orientation varies from being madly besotted with the other sex, through moderate attraction, through bisexuality to homosexuality. All outcomes a possible product of normal variation in a multifactorial system.

Now another layer of understanding. X and Y chromosomes pair up during meiosis before separating into sperms. The conventional text book idea is that they do not to cross over. But the X and Y are not holding a bible study group when they pair up. What if the X and Y very occasionally do exchange bits of information while paired up? So you get an X with a tiny bit of Y, and a Y with a tiny bit of X. In other words part of a natural process has opportunity and potential to produce a slightly shuffled deck in the sex genes. To my way of thinking that's just more normal variation. If it doesn't result in a heterosexual breeder, so what!? Some people are left handed and have red hair, so what!?

EDIT: And to answer the OP. Variation is natural and leads to evolution. Variation is the fuel of the engine of evolution. Homosexuality may have evolved partly because of benefits - I'm open to that idea because homosexuals do benefit society is several obvious ways, including specialisation and supporting families. But what I'm 100% sure of is that a range of sexuality is an inevitable consequence of natural variation. And without natural variation we wouldn't have evolved. We can't have one without the other.

X and Y do indeed crossover in the corresponding pseudoautosomal regions. The other unique sections are said not to exchange DNA. However, sequencing of Y chromosomes does show old bits of X DNA are present on the Y.

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The organization of the human Y chromosome thus reflects a combination of several evolutionary processes: the degeneration of the bulk of the genes, which were originally common to the primeval X/Y chromosome pair; the accumulation of genes with male-specific functions by sporadic transpositions from the X chromosome and autosomes; and a unique recent transposition of a large piece of X chromosomal material.

I would like to see sequencing of Y chromosomes of say a couple hundred unrelated homosexual males and their fathers - to rule out that there might be something going on between the X and Y during meiosis that ends up affecting sexuality. Other research has found evidence of recombination in the "unique" regions:

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There is new paper is out in American Journal of Human Genetics about how the X and Y chromosome might not be as separate as we think, and in fact might undergo regular recombination in certain regions ..... .... The authors say that this mechanism may play a part in the evolution of the other intersex abnormality genes (both known and current undiscovered), which probably undergo similar recombination events.

I think I understand what you're saying. I just can't help but think there is something missing. Something we still don't understand. Like what about pedophiles,necrophiliacs, or animal pervs. How do they benefit a society or a gene pool? IOW, How through natural selection did we get people like this. Why aren't we all well mannered, kind, empathetic's working together to build a strong society that functions without poverty or violence.

One point I would like to make is gays are often outcasts not the family babysitter. I am happy to say it's getting better but Most people still view being gay as unnatural.

I think I understand what you're saying. I just can't help but think there is something missing. Something we still don't understand. Like what about pedophiles,necrophiliacs, or animal pervs. How do they benefit a society or a gene pool? IOW, How through natural selection did we get people like this. Why aren't we all well mannered, kind, empathetic's working together to build a strong society that functions without poverty or violence.

One point I would like to make is gays are often outcasts not the family babysitter. I am happy to say it's getting better but Most people still view being gay as unnatural.

There is a natural variation, just as with intelligence. Not all of the variations will be pleasant but at least they will have less chance of producing another generation.

I think I understand what you're saying. I just can't help but think there is something missing. Something we still don't understand. Like what about pedophiles,necrophiliacs, or animal pervs. How do they benefit a society or a gene pool? IOW, How through natural selection did we get people like this. Why aren't we all well mannered, kind, empathetic's working together to build a strong society that functions without poverty or violence.

One point I would like to make is gays are often outcasts not the family babysitter. I am happy to say it's getting better but Most people still view being gay as unnatural.

Bolds mine.Junebug, you seem to have an incorrect idea about evolution, one that you've also expressed in the "Impossibility Argument"thread. That is, you seem to think evolution should lead to what you define as "perfection". I know you didn't actually use that word, but it certainly seems implied.

But evolution is undirected, and has no "goal" other than sheer survival. If enough humans are living to produce the next generation, the "goal" is met. Everything else, from an evolutionary standpoint, is irrelevant.

EDIT: And to answer the OP. Variation is natural and leads to evolution. Variation is the fuel of the engine of evolution. Homosexuality may have evolved partly because of benefits - I'm open to that idea because homosexuals do benefit society is several obvious ways, including specialisation and supporting families. But what I'm 100% sure of is that a range of sexuality is an inevitable consequence of natural variation. And without natural variation we wouldn't have evolved. We can't have one without the other.

As to quirks like pedophelia, necrophelia and beastiality, there are often environmental factors in their development (just as there are in homosexuality), and in some cases may be genuinely learned behavior without a genetic component. Those extreme variations in the human spectrum are likely being selected against, but it's a slow and undirected process.

As William has pointed out, human genetics is messy and hetero-normative people may carry unexpressed sex-drive regulating mutations that don't show over multiple generations. Then finally, in a particular child, enough of those variant traits become dominant enough to affect that person's behavior.

Again, except for human selective breeding of organisms, evolution is utterly without intention. It's a process, like water carving a canyon over millions of years. It's not about perfection, but just getting by.

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Live a good life... If there are no gods, then you will be gone, but will have lived a noble life that will live on in the memories of your loved ones. I am not afraid.--Marcus Aurelius

I think you miss my point. Evolution explains something but not origins. It does not explain morals, emotions, intelligence or conscientiousness. It explains adaptions to environments.

You don't have to completely understand it to get that. This is probably why I'm confused.

I can believe evolution and still believe in a Higher Power. It's not a problem.

If it were not for TOE the term survival of the fittest would not exist. So then why shouldn't I conclude the end product to be the fittest?

All this intelligent science shows me is how incredibly intelligent and patient the Inventor must be!!!

Hi,

In this context, the fittest just means best able to reproduce.

The origin of life is part of chemistry, a different subject. The reason this is not known is not because it is difficult. If all the stages still existed we could easily work out what happened using present day technology. The problem is that we are trying to deduce what happened from the result we have today, billions of years later.

I think I understand what you're saying. I just can't help but think there is something missing. Something we still don't understand. Like what about pedophiles,necrophiliacs, or animal pervs. How do they benefit a society or a gene pool? IOW, How through natural selection did we get people like this. Why aren't we all well mannered, kind, empathetic's working together to build a strong society that functions without poverty or violence.

One point I would like to make is gays are often outcasts not the family babysitter. I am happy to say it's getting better but Most people still view being gay as unnatural.

Uggh. You have to think of how a human transitions from a normal mammal to a brain-oriented, cooperative mammal.

One of the distinguishing features of mammals is that males compete for females, by beating each other up. Polygamy in Islam and Judaism is the tail end of it. If you have one man owning 3 women, then what are the remainder doing?

Given that the mammalian instinct is to rape a female, and then leave, beating up any males you pass on the way, it figures that some modifications have to made, in order to bring up slow-maturing children in a cohesive tribal situation. One thing that's important, is to start liking other males, and start loving females. In other words, the whole emotion dial has to be turned up.

There is not a great deal of sexual dimorphism in humans. Females, are smaller, and have some bumps on them, but otherwise, they say they are equal. How do you genetically attract people together, given that it's irrational? Other mammals' attraction is triggered by sense of smell. We don't have a sense of smell. The basis for our attraction is mental (logic).

To give us an incentive to get past the fact that children are a PITA, a burden, and deadly to have, we have evolved huge emotional eroticism. Given that all our emotions have been dialed up, and we are looking for a post to rub against to get to orgasm, and there is no physical/chemical stimulus to direct men at females, besides the fact that the penis fits into a vagina relatively well, then it follows that sexual direction is poorly targeted. If 100% of the females have been owned by 30% of the men, then the 70% of men left out, are going to start rubbing against something.

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Like what about pedophiles,necrophiliacs, or animal pervs.

Dial up emotions, fear, insecurity, bad parenting. Mix it in with rejection, and add a dressing of being over-attracted to vague things, and you have humans, rubbing themselves up against anything.

You know, a few years back I read an article which addressed the question of why human women do not die immediately following menopause. We no longer reproduce. We use resources. What possible purpose could we serve in society post menopause?

Well, the article addressed the fact that the survival of a species involves more than just passing on genetic material. We don't exist just as individuals. We live in communities, and as members of communities, we contribute to the survival of the community via a wide range of contributions. [1] The article speculated that in tribal societies, women who bore man children needed an extra set of hands to tend to the safety and well being of a large group, and that the role of the "grandmother" played a vital role in the survival of the community as a whole.

Childbearing, in spite of being obviously necessary for the survival of a community, places a huge burden on the parents as well as the larger community. It is harder to flee enemies. The mother is taken out of the larger workforce for a period of time, and her need for resources increases. General mobility of nomadic communities decreases.

There was clearly a need within ancient societies for members who are not currently reproducing, whether they are grandparents or people of childbearing age who are not bearing children.

In today's society, our structures have changed much faster than our genetic programming. Grandma lives in another state, and a the kids go to daycare when mom goes back to the office. Gay men and lesbians become parents and raise kids. Heterosexual individuals can decide if they want to parent, and have access to birth control (in many but not all societies) to limit their family size and either contribute more to work, or contribute more actively to the well-being of their smaller families.

You asked about the sources of "morals" and "emotions." I think that it is clear the empathy, and concern for the well-being of others are necessary components to survival. If a tribe needs to flee an enemy, the mother's survival would be increase if she abandoned her brood. But those who were programmed to protect their offspring were more likely to pass on the genetic material to future generations.

Unlike many here, I approach the world from a social science, rather than a hard science perspective. I welcome feedback from our hard scientists on this very interesting question.

If you are interested in learning more about the role that cooperation plays in natural selection, I highly recommend reading Mutual Aid by Peter Kropotkin, who was a contemporary of Darwin's, and who studied natural selection in the natural world during the same era. Kropotkin focused on cooperation, rather than competition as a contributing factor to survival.

Why aren't we all well mannered, kind, empathetic's working together to build a strong society that functions without poverty or violence.

I forgot to answer that ^

The empathetic utopia has few people dying in it, and evolution requires high death rates. Humans already have a 16-20yr generation gap, so in order to have progress, you need high selection rates. If you want to spread intelligence throughout a society, the most efficient way to do it, is to have all the smart ones wipe out the dumb ones, otherwise you have dumb genes persisting indefinitely. If you help people in a welfare system, you are just encouraging them to procreate, which is the opposite of what is required for progressive change. If you help the sick, you are encouraging sickness to succeed. If you find ways of curing the sickness, ditto. Evolution engineers by death. There is a dynamic tension between compassion and individual health fitness.

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When you have eliminated the impossible, whatever remains, however improbable, must be bleedn obvious.

I think that another reason (though it's been touched on in a number of responses here) is the fact that the human population no longer depends on just the "fittest" as it might in populations of other animals where natural survival ability dictates far more which individuals will live to pass on their genes. Human beings, especially in this day and age will tend far more to nurture and protect the weaker and less able. Not that this has anything to do with homosexuality, per se...just a notation of the fact that there is far, far more diversity in the human population than in wildlife, and very probably far more diversity in the human population in this day and age than in the past.

As others have said, also , there is a really wide range of sexual behaviors and preferences, and it's really all on a continuum, where a lot, maybe even a majority of people will fall somewhere outside of being (or at least feeling) exclusively, 100% heterosexual, 100% of the time. I think many people might be reluctant to even admit to or to examine within themselves. And as such, I think, there is nothing inherently "wrong" about them.

On the other hand, the issues of the preferences which are really out in left field, such as necrophilia, bestiality etc, are a really unfortunate offshoot which luckily does not affect more than a tiny percentage, and is probably exacerbated by environment or brain chemistry. Also, and I might be wrong, I think some of these things might show up more in the sociopathic personality, which is another question altogether. Maybe some of these tendencies might have been "weeded out" to some extent in the past in various ways ranging from execution to sterilization, to institutionalization beyond redemption, but there would still be carriers in the population (if the causes were, indeed, genetic), so I'm not sure how much of an impact that would have had. Anyway, it's the tip of a "slippery slope" argument to say some of these things are on the same continuum as homosexuality, and I'm not going to go there. Some may well be, but if the tendency involves hurting or taking advantage of another individual or innocent creature as opposed to simply allowing certain individuals the same rights to create a loving family structure as others, it's not the same thing at all.

Also, there are cultures which do embrace homosexual/tansgender personalities as alternate "sexes", and recognize their contribution. I don't doubt but that there are a lot of things which more feminine males and more masculine females can contribute to a society regardless of who they actually choose to sleep with.

The part here I can't get around is the same reason I don't like the biblical story of origins. It goes back to life started from 1 single cell organism. Which came first male or female. If they both came forth at the same time seems unlikely. Even more disturbing that the siblings of this 1 man and 1 woman had to reproduce between themselves which we call incest these days and consider it very unmoral.

I think there was probably more than 1 single cell organism, could that not be a possibility? I think there was probably 1 for each species male and female and that there were many so that several forms came forth. They must've been formed in the adult stage because babies could not have survived.

I've been told in another thread emotions do not change DNA so how does that fall under evolution? I know some very nice people who have had not so nice children. I also know terrible parents whose children turned out incredible.

So why is society so screwed up? We should have evolved immaculate social skills by now or social skills have nothing to do with evolution. There are still tribes that eat people out there. Why haven't they evolved?

William- I am sure we have the same definition for conscientiousness. Self-awareness. Our good/bad meter. Why are we the only species that got one and why do some work better than others?

Add-People will die no matter what. Rich people get sick and die too. You can not eliminate it by getting rid of poor people. That post is so sad. Helping people releases good chemicals in the brain, gives you a good feeling, and you are loved by all you touch and will be remembered, immortalized, by your kindness. It also would create a less violent world where your chances of being murdered drop dramatically. Desperate people do desperate things!

Whoever argued that homosexuality is a result of polygamy has the best argument. I can certainly live with that.